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Finding the Fourth Proportional to 139.87, 209.90 and 79.12

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Solution

The fourth proportional to 139.87, 209.90 and 79.12 is: 118.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.87 : 209.90 = 79.12 : x
  2. Step 2: Convert to fraction form
    139.87/209.90 = 79.12/x
  3. Step 3: Cross multiply
    139.87x = 209.90 × 79.12
  4. Step 4: Simplify right side
    139.87x = 16,607.29
  5. Step 5: Solve for x
    x = 16,607.29/139.87
  6. Step 6: Final answer
    x = 118.73

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.